Add GUI for Media Folder Settings

...all/assets/de/tobias/playpad/assets/lang/ui_de.properties

.../de/tobias/playpad/assets/view/option/global/keysTab.fxml

...de/tobias/playpad/assets/view/option/project/pathTab.fxml

...ypad/layout/desktop/DesktopMenuToolbarViewController.java

...viewcontroller/option/project/PathsTabViewController.java

...troller/option/project/ProjectSettingsViewController.java

...llCore/src/de/tobias/playpad/project/ProjectSettings.java